Ferro-titanium alloy and method of making same



Patented Feb. 13, 1934 PATENT OFFICE UNITED STATES FERRO-TITANIUM ALLOYAND METHOD MAKING SAME Maine N0 Drawing. Application August 14, 1931Serial No. 557,135

Claims.

My invention relates generally to titanium alloys for the treatment offerro-metals and more particularly to the methods of making such analloy for treating iron and steel to remove there- 5 from gaseous orother impurities that have injurious effects upon the metal and tomodify the properties of such metals by incorporating therewith itaniumand silicon.

The ferro-titanium alloys now in common use are made either with about7% carbon to insure freedom from the comparatively inactive nitride, orby the aluminothermic process to give a low-carbon alloy of low meltingpoint. Other ferro-titanium alloys containing silicon have beendescribed, but are not widely used, probably because of too high amelting point. The fusion temperature ofthese alloys varies directlywith the carbon content, so that for low melting points a low carboncontent is essential.

For general use as a deoxidizer and scavenger of molten steel, theferro-carbon-titanium containing about 7% carbon has awide field ofusefulness, and is the least expensive form of titanium available, onaccount of ease of manufacture. For certain purposes however a lowcarbon alloy is desirable, as for example, when a content of metallictitanium, as distinct from titanium-carbide, is desired in an alloysteel, or when the titanium alloy used must have a low fusiontemperature as in treating small quantities of steel or cast iron whererapid absorption of the alloy in the melt is essential.

The only alloys heretofore available for such purposes are thealumino-thermic ferro-titania um, which suffers from the objection'of analu minum content, not desired in many steels which must be as clean aspossible; and certain alloys containing titanium and silicon. Thelatter, as described in the literature, have been 40 made in such a wayas would inevitably result in a carbon content greatly above 1%, so thatthe fusion point would be not low enough to compensate for theadditional cost of such alloys as compared with the more generally usedand well known ferro-carbon-titanium.

I have discovered a new ferro-titanium alloy containing silicon, whichhas a low melting point and can be made without difliculty in anordinary electric furnace. The alloy contains not over 1% carbon, and itis also practically free from aluminum, thus permitting it to be used insteels Where no inclusions of alumina are permissible. It can be used toconfer the benefits of titanium-treatment on gray cast iron in smallladles, and the strength of the iron is increased about 25% by suchtreatment. strength iron may be made in small amounts when desired froma cupola-run of ordinary iron without changing the charge in the cupola.

When incorporated in the flux coating on electric welding rods in afinely-divided form, this improved alloy has been found to prevent theformation of oxide and nitride of iron in the depositedmetal, which isthus made similar in structure to a steel casting.

My improved titanium alloy is readily made in the usual carbon-linedfurnace by the simultaneous reduction of ilmenite which is aferroustitanate (FeTiOa)' containing about titanium oxide with thebalance iron oxide and silica rock or quartz containing about 98%silica. These ingredients are preferably crushed to about half-inchsize, though any size available between 40-mesh and one inch lumps maybe used. 1

Barley coal is used for reduction, and a small amount offerro-carbon-titanium, for example that described in the U. S. Rossi andMeredith Patent No. 1,039,672 of September 24, 1912, crushed to about toinch size, is added in place of the usual scrap iron in order toincrease the electrical conductivity of the charge. This substitution ofthe high-carbon titanium alloy for scrap-iron in the charge is anessential part of my improved methods, for by this means I have found itpossible to obtain a satisfactory content of titanium in the productwithout raising the carbon content too high for good fusibility. Ifscrap-iron is used in the charge, and the titanium content of theproduct is raised by increasing the proportion of titanium ore to silicain the charge, it is found that the carbon content rises with it,something I wish to avoid as hereinbefore described. But by usingferro-carbon-titanium in the charge in place of scrap-iron, it ispossible to so adjust the proportions of titanium ore and silica used asto obtain a new low carbon ferro-titanium alloy containing over 15%titanium with silicon content about 20% and not over 1% carbon.

Such alloy'made in this way contains 15 to Thus high- 25% each oftitanium'and silicon, and less than hon-titanium 12 to 18%; coal 12 to20%. The coal may be so distributed through the mix to be charged thatmore is added in the final portions of the furnace charge than in theportions that are in the furnace longer. The furnace should be chargedslowly, and should be tapped 20 to 30 minutes after the last of thecharge is melted,

silicon content about 20%, about 0.5% of carbon,

and the balance substantially iron.

3. In the method of making a low-melting, silicon-containing,term-titanium alloy, practically free from aluminum, the step whichconsists in reducing titaniferous ore and silica in a carbon-linedfurnace in the presence of ferrocarbon-titanium, the charge containing areducing agent and a preponderating amount of iron for the production ofsaid ferro-alloy having a titanium content above 15%, a silicon contentless than 25%, and carbon less than 1%.

4. In the method of making a low-melting ferro-titanium alloy the stepwhich consists in reducing in a carbon-lined electric furnace a chargecontaining approximately the following ingredients: ilmenite (30 to35%); silica (35 to 40%); ferro-carbon-titanium (12 to 18%); and coal(12 to 20%) to form a ferro-titanium alloy containing over 15% titaniumwith silicon content about 20% and not over 1% of carbon.

5. In the method of making a low-melting, silicon-containing,ferro-titanium alloy, practically free from aluminum, the step whichconsists in reducing in a carbon-lined electric furnace a chargecontaining approximately the following ingredients: ilmenite 32%; silica38%; ferro-carbon-titanium 15%; and coal 15%, to form a ferro-titaniumalloy containing over 15% titanium with the silicon content about 20%and not over 1% of carbon.

GEORGE F. COMSTOCK.

